In open-cast mining operations, it is often necessary to loosen overburden and the material to be mined to enable large power shovels and draglines to remove the overburden and mined material. The loosening work is best accomplished by the use of explosives placed at substantial depths in the overburden and material being mined.
Blasthole drills are used to drill into the overburden and material to be mined to the necessary depths to provide holes in which the explosives are placed. Drilling is often through hard rock, under very dirty conditions, and sometimes in very cold weather, making the work quite unpleasant. In order to reach the necessary depths at which the explosives must be placed, at least several and often a considerable string of drill shafts must be joined together at threaded joints as the drilling moves downward. When drilling is completed or if problems occur, the string of drill shafts must be raised and disassembled in a step-by-step manner. Due to drilling through hard material, the joining of the drill shafts together as drilling progresses downwardly, must be particularly tight. The continuous presence of dirt on the shafts and often the cold operating temperatures will also result in the joint being very tight. As a consequence, the disconnecting of each drilled shaft from another may be quite difficult. To assist with the problem of breaking joints when disconnecting drill shafts, before the shafts are threaded together at each joint, the drill operator is required to swab the exposed threaded joint with grease using a bucket of grease and a wire brush. However, operators do not consistently apply the grease due to factors such as poor weather conditions and a desire to hurry the work along. Lost production results due to later difficulty in breaking of the joints and damage to some threaded joints.